Optical bandpass/notch filter with independent tuning of wavelength and bandwidth based on a blazed diffraction grating

We propose a multifunctional optical filter based on a blazed diffraction grating. The optical filter can function as a bandpass filter or a notch filter. A theoretical model of the filter is built for analysis. Both bandwidth and wavelength of the filter can be independently and continuously tuned. In the experimental demonstration, the wavelength can be linearly tuned within the entire C-band and partial L-band. The bandwidths of the filter can be tuned from 1.3 to 6.4 nm (–3 dB bandwidth) and from 2.4 to 11.3 nm (–10 dB bandwidth) for bandpass function and from 6.9 to 11.9 nm (–3 dB bandwidth) and from 5.1 to 8.8 nm (–10 dB bandwidth) for band-stop function, respectively. The extinction ratio of more than 35 dB is achieved.